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Physical Science

Observations of binary stars containing an accreting black hole or neutron star often show x-ray emission extending to high energies (>10 kilo–electron volts), which is ascribed to an accretion disk corona of energetic particles akin to those seen in the solar corona. Despite their ubiquity, the physical conditions in accretion disk coronae remain poorly constrained.

Pluto’s atmosphere is cold and hazy. Recent observations have shown it to be much colder than predicted theoretically, suggesting an unknown cooling mechanism. Atmospheric gas molecules, particularly water vapour, have been proposed as a coolant; however, because Pluto’s thermal structure is expected to be in radiative–conductive equilibrium, the required water vapour would need to be supersaturated by many orders of magnitude under thermodynamic equilibrium conditions. Here the researchers report that atmospheric hazes, rather than gases, can explain Pluto’s temperature profile.

NASA's Cassini spacecraft continues to yield surprising discoveries, more than a month after it burned up on its mission-ending dive into Saturn. New data from the probe suggest that Saturn's majestic rings are showering tiny dust particles into the planet's upper atmosphere, where they form a complicated and unexpected chemical mix.

We present the survey strategy and early results of the “Satellites Around Galactic Analogs” (SAGA) Survey. The SAGA Survey’s goal is to measure the distribution of satellite galaxies around 100 systems analogous to the Milky Way down to the luminosity of the Leo I dwarf galaxy (Mr < -12.3).

When the Moon’s shadow races across the continental United States on 21 August, researchers will be waiting — in planes, on mountaintops and at other carefully chosen vantage points along the roughly 110-kilometre-wide path of totality. Thanks to the sheer number of observers, solar physicists hope to learn more from this latest total solar eclipse than from any previous such event, and to use that knowledge to develop tools for next time.

Giant radio galaxies (GRGs) are one of the largest astrophysical sources in the Universe with an overall projected linear size of ∼0.7 Mpc or more. The last six decades of radio astronomy research has led to the detection of thousands of radio galaxies. However, only ∼300 of them can be classified as GRGs. The reasons behind their large size and rarity are unknown. We carried out a systematic search for these radio giants and found a large sample of GRGs.

Rossby waves are a type of global-scale wave that develops in planetary atmospheres, driven by the planet’s rotation. They propagate westward owing to the Coriolis force, and their characterization enables more precise forecasting of weather on Earth. Despite the massive reservoir of rotational energy available in the Sun’s interior and decades of observational investigation, their solar analogue defies unambiguous identification.

Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets.

Solar magnetism displays a host of variational timescales of which the enigmatic 11-year sunspot cycle is most prominent. Recent work has demonstrated that the sunspot cycle can be explained in terms of the intra- and extra-hemispheric interaction between the overlapping activity bands of the 22-year magnetic polarity cycle. Those activity bands appear to be driven by the rotation of the Sun’s deep interior. Here we deduce that activity band interaction can qualitatively explain the ‘Gnevyshev Gap’—a well-established feature of flare and sunspot occurrence.